1. Field of the Invention
The present invention relates generally to Ethernet systems and, more particularly, to a system and method for enabling legacy media access control to do energy efficient Ethernet (EEE).
2. Introduction
Energy costs continue to escalate in a trend that has accelerated in recent years. Such being the case, various industries have become increasingly sensitive to the impact of those rising costs. One area that has drawn increasing scrutiny is the IT infrastructure. Many companies are now looking at their IT systems' power usage to determine whether the energy costs can be reduced. For this reason, an industry focus on energy efficient networks has arisen to address the rising costs of IT equipment usage as a whole (i.e., PCs, displays, printers, servers, network equipment, etc.).
In designing an energy efficient solution, one of the considerations is the traffic profile on the network link. For example, many network links are typically in an idle state between sporadic bursts of data, while in other network links, there can be regular or intermittent low-bandwidth traffic, with bursts of high-bandwidth traffic. An additional consideration for an energy efficient solution is the extent to which the traffic is sensitive to buffering and latency. For example, some traffic patterns (e.g., HPC cluster or high-end 24-hr data center) are very sensitive to latency such that buffering would be problematic. For these and other reasons, applying energy efficient concepts to different traffic profiles would lead to different solutions. These varied solutions can therefore seek to adapt the link, link rate, and layers above the link to an optimal solution based on various energy costs and impact on traffic, which itself is dependent on the application.
As would be appreciated, an EEE solution typically requires coordination between various layers. For example, an EEE mechanism can be implemented in a physical layer device (PHY) to transition the PHY between various energy states. In supporting these various PHY energy states, the MAC and upper layers (including silicon, software and firmware) would also need to control its operation to implement the EEE control policy. Ideally, a MAC-containing device would be enhanced to accommodate such an EEE mechanism. Otherwise, any PHY innovations for EEE would be rendered useless in systems that contain legacy MAC silicon. What is needed therefore is a mechanism that enables legacy MACs to cooperate with an EEE-enabled PHY.